That's higher than the 2012 turnout rate but lower than the 60 percent turnout for the February 2008 presidential primary.

Still, according to the report, voter registration in the state is experiencing "historic growth" with more than 850,000 Californians registering to vote in the first three months of the year. An analysis of the San Diego County Registrar of Voters found registration jumped a net 50,977 voters from January to April 2016.

"The last time we saw an increase in registration before a presidential primary you have to go back to Ronald Reagan in 1980,” Vince Vasquez, senior policy analyst at National University System Institute for Policy Research, told KPBS Midday Edition on Monday.

"By the time we reach the final voter registration deadline this month, we could have somewhere in the neighborhood of 200,000 new voters in San Diego County, half of which live in the city of San Diego," Vasquez said.

According to the report, more than 51 percent of newly registered voters are millennials. They also lean democratic compared to San Diego's overall electorate and are more diverse, with an uptick in Latino voter registration.

"Demographically, they largely fit the profile of Bernie Sanders supporters," Vasquez said. "How many will vote down ticket, and what are the campaigns doing to appeal to these new voters? We’ll find out on election night.”

The last day to register to vote for the June election is May 23.

Photo credit: National University System Institute for Policy Research

This table shows new voter registrants in San Diego County as compared to all registrants in the county.